CVE-2021-30663
HighExploitedPublic exploitwebkitgtk: Integer overflow leading to arbitrary code execution
Published Oct 13, 2021 · Updated Aug 4, 2026 · Also known as DEBIAN-CVE-2021-30663, UBUNTU-CVE-2021-30663
Key Facts
Patch immediately- CVE-2021-30663 is a high-severity vulnerability (CVSS 7.8 v3.1) affecting Safari (Apple), Ipados (Apple), Iphone OS (Apple) and 22 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 3, 2021. Public exploit code is available.
- EPSS estimates a 3.5% probability of exploitation in the next 30 days.
- Fixed versions are available, including accountsservice 0.6.55-2.el8, accountsservice-devel 0.6.55-2.el8, accountsservice-libs 0.6.55-2.el8.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
7.8
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
3.5%
Higher than 89.0% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-30663 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Not reported |
| Industry KEV feed | May 3, 2021 | Nov 17, 2021 | Not reported |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Not reported |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
480 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| SafariApple | See advisory | 14.1.1 |
| IpadosApple | See advisory | 14.5.1 |
| Iphone OSApple | See advisory | 12.5.3 |
| macOSApple | >= unspecified | 11.3.1 |
| TvosApple | See advisory | 14.6 |
Patched Releases
accountsservice
0.6.55-2.el8
accountsservice-devel
0.6.55-2.el8
accountsservice-libs
0.6.55-2.el8
Ipados
14.5.1
Iphone OS
12.5.3
macOS
11.3.1, 11.3, 12.5, 14.1, 14.5, 14.6
Safari
14.1.1
Tvos
14.6
gdm
1:40.0-15.el8
gnome-autoar
0.2.3-2.el8
gnome-calculator
3.28.2-2.el8
gnome-classic-session
3.32.1-20.el8
gnome-control-center
3.28.2-28.el8
gnome-control-center-filesystem
3.28.2-28.el8
gnome-online-accounts
3.28.2-3.el8
gnome-online-accounts-devel
3.28.2-3.el8
gnome-session
3.28.1-13.0.1.el8, 3.28.1-13.el8
gnome-session-kiosk-session
3.28.1-13.0.1.el8
gnome-session-wayland-session
3.28.1-13.0.1.el8
gnome-session-xsession
3.28.1-13.0.1.el8
gnome-settings-daemon
3.32.0-16.el8, 3.32.0-16.el8_6.1, 3.32.0-16.el8.alma
gnome-shell
3.32.2-40.el8
gnome-shell-extension-apps-menu
3.32.1-20.el8
gnome-shell-extension-auto-move-windows
3.32.1-20.el8
gnome-shell-extension-common
3.32.1-20.el8
Timeline
Added to Industry KEV feed
May 3, 2021
Publicly disclosed
Oct 13, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Aug 4, 2026
Weakness Type
- CWE-190 Integer Overflow or Wraparound
References
- advisoryhttp://feedproxy.google.com/~r/TheHackersNews/~3/elwYiDkfEBM/apple-releases-urgent-iphone-and-ipad.html
- advisoryRHSA-2021:4381
- advisoryRHSA-2025:10364
- advisoryhttps://bugzilla.suse.com/1188697
- advisoryhttps://saaramar.github.io/IOMFB_integer_overflow_poc/
FAQ
Common Questions.
An integer overflow was addressed with improved input validation.
Affected: Safari (Apple); Ipados (Apple); Iphone OS (Apple), among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 3, 2021.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
Fixed versions are available, including accountsservice 0.6.55-2.el8, accountsservice-devel 0.6.55-2.el8, accountsservice-libs 0.6.55-2.el8.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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